GAZA CITY, Feb 2: Palestinian president Mahmud Abbas and exiled Hamas political supremo Khaled Meshaal on Friday declared a ceasefire between their feuding factions in the Gaza Strip after internecine violence killed 25 people in just 24 hours.

Shortly after the ceasefire was announced, unknown gunmen opened fire on the motorcade of the Egyptian envoy to the Gaza Strip, who has been at the heart of mediation efforts between Abbas's Fatah and the ruling Hamas faction.

There were no injuries in the incident which cast doubts on the chances of the ceasefire, which came three days after the declaration of another truce.

“President Mahmud Abbas and Hamas political chief Khaled Meshaal held a phone conversation this evening and agreed to make an effort to end the fighting,” presidential spokesman Nabil Abu Rudeina said.

The two leaders also agreed to meet in Makkah next Tuesday on the initiative of King Abdullah of Saudi Arabia, he added.

Nizar Rayan, a Hamas official in the Gaza Strip, confirmed that “Abbas and Meshaal reached an agreement between Fatah and Hamas on an immediate ceasefire.” Black smoke billowed into the sky from Gaza's Islamic University on Friday after the Hamas bastion was stormed overnight by Abbas's presidential guard and gunfire and mortar attacks erupted across the territory, also spreading to the West Bank.

Sixty Palestinians have been killed since Jan 25 in the deadliest factional fighting since Hamas won a general election last year, limiting the once-dominant Fatah's grip on power to the presidency.

Nineteen people died on Friday alone, including a seven-year-old child, a 38-year-old woman, two teenagers, three presidential guardsmen and a deputy intelligence commander.

Masked fighters from Hamas and Fatah roamed the largely deserted streets to the rattle of gunfire as representatives of the rival parties met in Gaza City.

Six Palestinians, including four pro-Fatah security officers and a Hamas militant, were killed on Thursday. Around 185 people have been wounded.

The Abbas-Meshaal summit will be a second rare meeting for the two leaders after talks in Damascus on Jan 21 ended without a breakthrough to halt the power struggle that has seen around 100 people killed since Hamas's election win a year ago.

“King Abdullah's call for dialogue in Makkah is very important and we are going to respond favourably as soon as we receive an official invitation from the kingdom,” Abbas said on Friday.

Between 40 and 50 presidential guard recruits were wounded when Hamas militants and members of a controversial Executive Force controlled by the Islamist government fired a mortar round into their training camp in Gaza City.

A huge fire broke out at the Islamic University in Gaza City, a Hamas bastion and the most prestigious centre of higher education in the impoverished territory, after it was stormed by presidential guards overnight.

The operation was ordered after Hamas militants on the campus fired mortar rounds and rocket-propelled grenades at presidential offices.

Hamas condemned the storming of the university and accused Fatah of transporting “American-Zionist arms.” The clashes began when Hamas ambushed a presidential guard convoy that Fatah denied was shipping weapons.

The presidency blamed Hamas for the violence amid increasing international pressure on the factions to resolve their differences and negotiate a power-sharing agreement.

Fatah, moderate and secular, and Hamas, radical and Islamist, have tried for months to form a national unity government acceptable to Western donors in the hope of ending a crippling aid freeze.

Hamas has steadfastly rejected Western demands that it renounce violence and recognise Israel and past peace deals.

While the Palestinian leaders struggled to quell the violence in Gaza, the so-called Quartet of major players in the Middle East peace process expressed concern over the ongoing violence following a meeting in Washington.

Representatives of the Quartet -- the European Union, Russia, the United Nations and the United States -- also welcomed US efforts to accelerate a road map to create a Palestinian state.

But they also reaffirmed the economic and diplomatic boycott on the Hamas-led government.

UN Secretary General Ban Ki-moon told a news conference that the boycott could only be lifted if Hamas agreed to recognize Israel's right to exist and renounced violence, or is replaced by a government that will meet those conditions.

Palestinian foreign minister Mahmud al-Zahar earlier urged the Quartet in a letter “to open a dialogue with the Palestinian government in order to reach stability and calm in the region,” his spokesman said.—AFP